Citalopram is one type of antidepressants known as Selective Serotonin Re-uptake Inhibitors (SSRIs). It increases the effects of the body’s naturally occurring hormone, serotonin, by inhibiting its re-uptake in the nerve cells.

Serotonin is said to be reduced in cases of Depression, therefore by inhibiting the reuptake (removal) of Serotonin in the brain, Citalopram help increase it's level to near about normal and helps treat depression.